1. Field of the Invention
This invention relates generally to treatment of fluids and more particularly to a method for increasing the efficiency of filter media in the removal of unwanted contaminants, such as chlorine, from hot water during showering.
2. Description of Related Art
Starting after the U.S. Civil War, the recognition and linking of macroscopic and microscopic pathogens to the aesthetic and health qualities of water resulted in the search for effective water disinfection and treatment procedures. Soon thereafter, chlorine was identified as a disinfecting agent. Towards the end of the 19th century, there were several recorded instances of the use of chlorine compounds for the disinfection of water and, with increasing experience, the effectiveness of chlorine treatment of water became more widely recognized and appreciated. The introduction of water chlorination, as a continuous process, occurred soon after the turn of the century. Currently, approximately 80% of all potable water systems in the U.S. contain chlorine as a disinfectant.
Different devices and methods for dechlorination of water have been used both at the point-of-entry ("POE") into a commercial, industrial or residential building, and the point-of-use ("POU") at the faucet, shower head or tap.
POE systems typically are in the form of an aerator, or a large organic or inorganic filtering media bed. Although applicable in some instances, these systems have potential problems, and have fallen under close scrutiny, due to the possibility of pathogenic reintroduction back into the water system, after the point of dechlorination. Because of this possibility, and the recent advancement in water treatment technology, POU water treatment systems have become widely accepted and are now primarily used in residential, and to a large degree, in commercial and industrial applications.
Both organic and inorganic filtering media are known for use in dechlorination. Carbon (organic) filtering media are used either alone, or in conjunction with other systems, such as reverse osmosis or distillation, or may be used with inorganic filtering media, such as cation/anion resins.
Currently, shower filters are known which use various types of materials to filter out impurities in water. However, the performance of such shower filters is restricted by the water's high flow rate and the high temperatures of the water. Traditional filtration methods have historically relied on carbon as the filtration media, using the process of adsorption to remove contaminants such as chlorine. The mechanics of adsorption involve a finite number of molecular attachment sites located in each granule of activated carbon. Often compared to a sponge, carbon "pulls" contaminants out of the water by an electrochemical charge located at each site. Used for removing the free and combined (or total) chlorine from drinking water at typically lower flow rates and at room temperature (25 degrees C.), carbon is quite effective.
However, carbon's shower water filtration efficiency is limited by the higher flow rate and high temperatures of shower water. In fact, carbon has a tendency to release previously adsorbed contaminants back into the water stream when temperatures approach the contaminants' boiling or vaporization point. Chlorine has a relatively low vaporization point. The releasing (off-loading) of chlorine begins when the water temperature is at about 90 degrees.
A partial solution to filtration of shower water at high temperatures and flow rates came with the use of granular copper and zinc. This media utilizes different filtration mechanics. Instead of pulling contaminants out of the water through the process of adsorption, as the carbon does, the copper and zinc (being very dissimilar metals) create an increased electro-negative potential in the water. Free chlorine is converted to an FDA "food grade" safe substance, zinc-chloride. This process is rather selective. Even though the free chlorine is converted, the many molecular combinations of chlorine (combined chlorine) are not affected, and remain in the water.
It is the free (uncombined) chlorine that is introduced into the water for disinfection purposes. It easily passes through the cell wall of the pathogen and attaches to the fatty acids in the cell creating complex chloro-compound. Once this occurs, cell functions cease and pathogen dies. The same processes occur when the human body is exposed to chlorine. Symptoms of chlorine exposure ranges from dry, itchy-flaking skin, scalp and hair to epidermal rash, and even to colon, liver and bladder cancer. Effective as copper-zinc filtration is, it also has its limits. In the case of chlorine, it is chlorine-free specific. That is to say that it only affects the free chlorine and not the combined chlorine. Copper-zinc has two main problems: 1) it cannot convert the multitude of combined chlorines; 2) it requires a temperature environment of over 90 degrees (F) to effectively convert the free chlorine.
Another type of prior art filter media is disclosed in U.S. Pat. Nos. 4,642,192 and 5,122,274, which disclose an "electronegative cell potential type" chlorine filter media. The preferred media to filter out chlorine disclosed in these patents is brass (a mixture of copper and zinc).
Two types of shower filters devices are disclosed in U.S.
Pat. Nos. 5,152,464 and 5,300,224 to Fredrick A. Farley. The devices disclosed in these patents are compact filter assemblies containing a filtering media, such as copper and zinc, to filter out unwanted chlorine in water passing through the filters.
U.S. Pat. No. 2,582,388, discloses another prior art water filter, for insertion into a waterline, having two parts threaded together to form a shell or housing, with a plurality of screens held in an inlet to and an outlet from the interior thereof. Layers of activated charcoal, separated by a layer of silica and screens are arranged in the shell to filter water passing therethrough.
U.S. Pat. No. 3,760,951, incorporates 2,582,388 therein by reference, and discloses a similar water filter for insertion into a waterline by means of quick-disconnect bayonet fittings that allow the filter to be easily removed for cleaning or replacement.
U.S. Pat. No. 3,780,869, discloses a water filter, for insertion into a waterline, having a plurality of compartments with multiple filtering elements of sheep's wool therein.
U.S. Pat. No. 3,822,018, discloses a water filter, for insertion into a waterline, having two hemispherical sections joined together by threaded portions. The filter has a plurality of cylindrical filter elements annularly arranged therein containing natural wool, charcoal, cork and the like, and includes a valve for directing water through the filter elements or for directing water through the device, unfiltered.
U.S. Pat. No. 4,107,046, discloses a filter cartridge for an internally by-passable water purifier apparatus. The apparatus includes valve means for directing water through the filter cartridge, which contains granulated carbon mixed with a silver zeolite, and may be sandwiched between fibrous sheets of material, such as felt, before it exits the apparatus.
U.S. Pat. No. 4,172,796, discloses a water faucet having a water purification or filtering means, made from activated carbon, or carbon with oligodynamic silver, formed therein.
U.S. Pat. No. 4,504,389, discloses a water faucet having a separate housing containing a removable cartridge or filter element made from various stages of polyethylene and activated carbon particles therein.
U.S. Pat. No. 5,008,011, discloses a shower dechlorinator fabricated in the form of a short cylindrical filter housing having two separate end caps with inlet and outlet means for attachment between the outlet pipe for a shower and a shower head. The filter housing is filled with granulated or randomly oriented fibrous material in the form of a copper-zinc metal alloy.
While the foregoing prior art devices, filter media and methods provide improved filtration of water passing through them, they are not adapted to meet the health and safety standards of today, nor do they meet the requirements, such as in homes, that larger volumes of heated water having increased amounts of unwanted impurities therein be safely filtered out during showering. Furthermore, while the above-mentioned prior art provide some limited improvements in the filtering art, there remains the need in the art for a method that provides the most efficient filtering out of unwanted materials, such as chlorine, from hot water during showering, while at the same time meeting the more stringent health and safety regulations of local communities and such governmental agencies as the EPA.